Kinetic Monte Carlo Model for the Precipitation of High-Energy Protons and Hydrogen Atoms into the Atmosphere of Mars with Taking into Account the Measured Magnetic Field

Abstract

Results of model computations of the interaction of the high-energy protons and hydrogen atoms (H/H⁺) precipitating into the Martian atmosphere are presented. These computations were performed using a modification of the kinetic Monte Carlo model developed earlier for the analysis of the data from the MEX/ASPERA-3 instrument onboard the Mars Express spacecraft and the MAVEN/SWIA instrument onboard the MAVEN spacecraft. In this modification of the model, an arbitrary (three-dimensional) structure of the magnetic field of Mars is taken into account for the first time. With local measurements of all three components of the magnetic field, not only the flux of protons penetrating into the atmosphere, but also the degradation of the H/H⁺ flux along the spacecraft orbit and the formation of upward fluxes of protons and hydrogen atoms scattered by the atmosphere, can now be described. A comparison of simulations and measurements of proton fluxes at low altitudes are used to infer the efficiency of charge exchange between the solar wind and the extended Martian hydrogen corona. It was found that the induced magnetic field plays a very important role in the formation of the proton flux back-scattered by the atmosphere and strongly controls its magnitude.